1. Field of the Invention
The present invention relates to a polyarylene sulfide resin composition. Precisely, it relates to a well-balanced polyarylene sulfide resin composition having good fluidity and capable of being molded into moldings with good flexural strength.
2. Description of the Related Art
Polyarylene sulfide resins are referred to as super-engineering plastics, and have many applications, for example, to car parts, electrical and electronic parts and others, as having the advantages of heat resistance, flame retardancy, rigidity, solvent resistance and electrical insulation.
However, for car engine parts and others that are exposed to severe surroundings, resin compositions comprising conventional polyphenylene sulfide resins as compounded and reinforced with glass fibers are unsatisfactory, as their mechanical strength is not on the practicable level.
For improving the resin compositions, various methods have heretofore been proposed. For example, one comprises adding a coupling agent thereto (see JP-A 63-251430, 3-12453, 9-31632); another comprises blending polymers such as polysulfones and others (see JP-A 63-130662). However, these are still unsatisfactory.
The object of the invention is to provide a well-balanced polyarylene sulfide resin composition having both good fluidity and good mechanical strength.
We, the present inventors have assiduously studied the problems noted above, and have completed the present invention which is as follows:
[1] A polyarylene sulfide resin composition of which the spiral flow length, x (mm), to give a molding having a thickness of 1 mm and the flexural strength, y (MPa), of the molding satisfy the following numerical formula (I):
yxe2x89xa7xe2x88x92(3x/10)+340xe2x80x83xe2x80x83(I) 
wherein x falls between 100 and 300.
[2] The polyarylene sulfide resin composition of [1], which comprises (A) from 50 to 70 parts by weight of a polyarylene sulfide resin, (B) from 30 to 50 parts by weight of glass fibers, and (C) from 0 to 3 parts by weight, relative to 100 parts by weight of the polyarylene sulfide resin (A), of a coupling agent.
[3] A polyarylene sulfide resin composition, which comprises (A) from 50 to 70 parts by weight of a polyarylene sulfide resin as prepared by copolymerizing an essential monomer of the following formula (III) with a comonomer of the following formula (II) in a ratio of the comonomer to the total of the comonomer and the essential monomer of falling between 0.5 and 15 mol %, (B) from 30 to 50 parts by weight of glass fibers, and (C) from 0 to 3 parts by weight, relative to 100 parts by weight of the polyarylene sulfide resin (A), of a coupling agent. 
wherein X1 represents a halogen atom, and plural X1""s may be the same or different; A represents an OH group; and j falls between 1 and 4, 
wherein X2 represents a halogen atom, and plural X2""s may be the same or different; R1 represents an alkyl group having from 1 to 6 carbon atoms, or an aryl or arylalkyl group having from 6 to 20 carbon atoms, and plural R1""s may be the same or different; and h falls between 0 and 4.
[4] The polyarylene sulfide resin composition of [3], which satisfies the condition of the numerical formula (I) as in [1].
[5] The polyarylene sulfide resin composition of [3] or [4], wherein the polyarylene sulfide resin is a copolymer of p-dichlorobenzene and 2,4-dichiorophenol.
[6] A polyarylene sulfide resin composition, which comprises (A) from 50 to 70 parts by weight of a polyarylene sulfide resin as prepared by copolymerizing an essential monomer of the following formula (III) with a comonomer of the following formula (IV) in a ratio of the comonomer to the total of the comonomer and the essential monomer of falling between 0.5 and 15 mol %, (B) from 30 to 50 parts by weight of glass fibers, and (C) from 0 to 3 parts by weight, relative to 100 parts by weight of the polyarylene sulfide resin (A), of a coupling agent. 
wherein X3 represents a halogen atom, and plural X3""s may be the same or different; B represents an OH group or an NH2 group, and plural B""s may be the same or different; k falls between 1 and 4; Y represents a single bond, CH2, SO2, NH, O, CO, oranalkylidene, alkylene orpolymethylene group having from 2 to 20 carbon atoms, 
wherein X2 represents a halogen atom, and plural X2""s may be the same or different; R represents an alkyl group having from 1 to 6 carbon atoms, or an aryl or arylalkyl group having from 6 to 20 carbon atoms, and plural R1""s may be the same or different; and h falls between 0 and 4.
[7] The polyarylene sulfide resin composition of [6], which satisfies the condition of the numerical formula (I) as in [1].
[8] The polyarylene sulfide resin composition of [6] or [7], wherein the polyarylene sulfide resin is a copolymer of p-dichlorobenzene and 3,3xe2x80x2-dichloro-4,4xe2x80x2-diaminobiphenyl.
[9] A polyarylene sulfide resin composition, which comprises (A) from 50 to 70 parts by weight of a polyarylene sulfide resin as prepared by polymerizing an essential monomer of the following formula (III) in the presence of a terminating agent of the following formula (V) in a ratio of the terminating agent to the total of the terminating agent and the essential monomer of falling between 0.5 and 5 mol %, (B) from 30 to 50 parts by weight of glass fibers, and (C) from 0 to 3 parts by weight, relative to 100 parts by weight of the polyarylene sulfide resin (A), of a coupling agent. 
wherein X4 represents a halogen atom; D represents an OH group; and k falls between 1 and 5, 
wherein X represents a halogen atom, and plural X2""s may be the same or different; R1 represents an alkyl group having from 1 to 6 carbon atoms, or an aryl or arylalkyl group having from 6 to 20 carbon atoms, and plural R1""s may be the same or different; and h falls between 0 and 4.
[10] The polyarylene sulfide resin composition of [9], which satisfies the condition of the numerical formula (I) as in [1].
[11] The polyarylene sulfide resin composition of [9] or [10], wherein the polyarylene sulfide resin is a polymer of p-dichlorobenzene with p-bromophenol and/or p-chlorophenol.